Basic Summary Statistics words

Question	Answer
Mean	Another word for average. Mean almost always refers to arithmetic mean.
Mode	The number that occurs the most often in a list.
Median of a Set of Numbers	Median of a Set of Numbers The median of a set of numbers is the value for which half the numbers are larger and half are smaller. If there are two middle numbers, the median is the arithmetic mean of the two middle numbers.
Quartiles	The collective term for the first quartile and third quartile of a set of data. That is, the 25th and 75th percentiles.
First Quartile, Q1	For a set of data, a number for which 25% of the data is less than that number. The first quartile is the same as the median of the data which are less than the overall median. Same as the 25th percentile.
Third Quartile, Q3	For a set of data, a number for which 75% of the data is less than that number. The third quartile is the same as the median of the part of the data which is greater than the median. Same as 75th percentile.
Interquartile Range, IQR	The difference between the first quartile and third quartile of a set of data. This is one way to describe the spread of a set of data.
Five number summary	For a set of data, the minimum, first quartile, median, third quartile, and maximum. Note: A boxplot is a visual display of the five-number summary.

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	Created by Lilian PS Tan about 11 years ago

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